Smart antenna for airborne cellular system

ABSTRACT

An airborne repeater antenna array ( 70 ) in which beams transmitted from multiple antenna elements ( 80 ) of the array to form terrestrial communications. cells are shaped according to predetermined system parameters. At least one of airplane telemetry data ( 58 ) indicating an airplane flight pattern location, adjacent cellular system beam footprint data, and call distribution load within a terrestrial cell are received, and a complex gain is dynamically computed for each of the multiple antenna elements based on such data to thereby output a plurality of beams that form desired geographic communications coverage cells ( 100, 102, 104, 108 ).

CROSS-REFERENCE TO RELATED APPLICATION

The present application is related to, and claims priority from,provisional patent application serial No. 60-153620, entitled WirelessAERO Solutions for Communications Networks, filed on Sep. 13, 1999, thecontents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to a wireless communicationssystem including an airborne repeater, and particularly to a smartantenna for use in such a system that is capable of beam steering andshaping and that compensates for motion of an airplane.

BACKGROUND OF THE INVENTION

The increasing need for communications networks and capabilities inoutlying and geographically diverse locations has created greater demandfor cellular systems. Many new carriers providing the infrastructure forsuch systems have focused their resources on building as manyterrestrial cell stations as possible to expand their respective areasof coverage and consequently generate more revenue.

However, the buildout rate for the terrestrial cell stations istypically slow and expensive, especially in mountainous or otherwisedifficult to access areas. In addition, in some of these areas, acarrier's return on investment may not provide the incentive necessaryfor the carrier to build the necessary cell stations, thereby leavingthese areas with either limited or no cellular service at all. Further,many areas having a sufficient number of cellular communications basetransceiving stations to handle calls during both off-peak and peaktimes cannot adequately handle large volumes of calls during sportingevents or other short-term special events that temporarily attract largecrowds.

In response to the above, airborne cellular systems have been proposedin which a cellular repeater mounted in an airplane, flying apredetermined flight pattern over a geographic area, links calls fromcellular phones within the covered geographic area to a terrestrial basestation. Because the airplane is capable of traversing geographiclimitations and takes the place of the cell stations, such a systemovercomes the above-mentioned limitations of conventional terrestrialcellular systems.

Despite its many advantages, an airborne cellular system presents designand implementation problems not present in the design and implementationof conventional terrestrial cellular systems. For example, as theairplane circles in its flight pattern, communications beams radiatedfrom the airplane antenna move relative to the ground, thereby causingthe system to perform call handoffs as beams rotate into and out ofpredetermined system areas of coverage. In addition, cellular systemsadjacent to the airborne system present potential beam interferenceissues. Large call loads in certain areas and small call loads in otherareas also tend to require an airborne system to provide more power, andconsume more radio spectrum, than would be necessary if the call loadsin each area were balanced. In addition, multipath Doppler and delayspread within an airborne system depends on the underlying terraincharacteristics and the speed of the aircraft and are more pronouncedthan in a conventional terrestrial cellular system, which may reduce theperformance of existing user handsets. Also, variations in airplanepitch, roll and yaw can move communications beams off-target and resultin interference with other cellular systems and therefore in systemnon-compliance with FCC regulations. Further, nonuniform subscriberdensity results in less efficient use of spectrum because the spectralcapacity of each beam must be sized for the maximum density region.Clearly a need exists for solution to the foregoing problems.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will be readily apparent from thefollowing detailed description of preferred embodiments thereof whentaken together with the accompanying drawings in which:

FIG. 1 is a system diagram of an airborne cellular communications systemof the type in which beam shape and direction are controlled accordingto the present invention;

FIG. 2 is a block diagram illustrating the components of the airbornecellular communications system shown in FIG. 1 in more detail;

FIG. 3 is a side elevation view of a phased array antenna of the type inaccordance with a preferred embodiment of the present invention, as wellas of communications beams radiated from the antenna;

FIG. 4 is a schematic diagram of an exemplary beamformer;

FIG. 5 is a block diagram showing the components used to generate thecomplex antenna gain coefficients used to shape beams output from thesmart antenna according to the present invention;

FIG. 6 is a diagram showing the major and minor axes of an exemplarybeam footprint shaped according to complex antenna gain coefficients;

FIG. 7 is a plan view of a plane in a first flight pattern positionincluding a repeater payload that radiates beams that provide cellularcoverage to a geographic area below and that are shaped by the antennaof FIG. 3; and

FIG. 8 is a plan view of the plane in FIG. 7 showing that beams radiatedfrom the airplane antenna remain stationary with respect to thegeographic area below, even as the airplane executes its flight pattern.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings in which like numerals reference likeparts, FIG. 1 shows an airborne cellular communications system 10. Thesystem 10 generally includes three primary segments: a cellularinfrastructure segment 12, a radio infrastructure segment 14, and anairplane segment 16. These three segments in combination are capable ofproviding cellular communications coverage to a large geographical areaby enabling system users, represented generally by handsets 18, to linkto a public switched telephone network (PSTN) 20 via an airplane payload22 including a repeater. The structure and function of each of thesethree system segments will be discussed in detail.

The cellular infrastructure segment 12 includes a mobile switchingoffice (MSO) 24 that includes equipment, such as a telephony switch,voicemail and message service centers, and other conventional componentsnecessary for cellular service. The MSO 24 connects to the PSTN 20 tosend and receive telephone calls in a manner well known in the art. Inaddition, the MSO 24 is connected to an operations and maintenancecenter (OMC) 26 from which a cellular system operator manages thecellular infrastructure segment 12. The MSO 24 is also connected to oneor more base transceiver stations (BTSs) such as the BTSs shown at 30 a,30 b. The BTSs 30 a, 30 b transmit and receive RF signals from thesystem users 18 through the radio infrastructure segment 14.

More specifically, the BTSs 30 a, 30 b transmits and receives RF signalsthrough ground converter equipment 32. The ground converter equipment 32converts terrestrial cellular format signals to C-band format signalsand communicates with the airborne payload 22 through a feeder link 33and a telemetry link 34, each of which will be discussed later indetail. The payload 22 establishes a radio link 36 for connecting callsover a wide geographic area of coverage, or footprint, that is capableof exceeding 350 km when the airplane maintains a flight pattern at oraround 30,000 feet above the ground.

In addition to the airplane 35, the airplane segment 16 also includes anairplane operations center 37 that controls mission logistics based atleast in part on information from sources such as a weather center 38,and manages all system airplanes, as the system preferably includesthree airplanes to ensure continuous coverage. The airplane alsoreceives additional routine instructions from sources such as an airtraffic control center 40.

FIG. 2 shows certain components of the system 10 in more detail.Specifically, the ground converter equipment 32 includes two C-bandantennas 42 for receiving/transmitting signals from/to the payload 22,and a C-band converter 44 for appropriately converting the signalsreceived from or to be transmitted to the payload 22. According to apreferred embodiment, the C-band antennas 42 and the converter 44 enable800 MHz airborne cellular smart antennas 70 to communicate with the BTSs30 a, 30 b via an established downlink, or feeder link, 33, and theconverter 44 upconverts nominal signals from the BTSs 30 a, 30 b toC-band signals before the signals are transmitted to the airplane 35.Also, each BTS 30 a, 30 b is assigned a different slot in the C-bandspectrum so that signals from the different BTSs 30 a, 30 b can beseparated and routed to the correct beam at the payload 22. In addition,the ground control equipment 32 includes telemetry components such as atelemetry antenna 46, a telemetry modem 48 and a telemetry processor 50to receive and process airplane data transmitted from an airplanetelemetry antenna 52, while a control terminal 54 controls transmissionof the processed telemetry data to the OMC 26 and the airplaneoperations center 37.

In the airplane segment 16, the airplane telemetry antenna 52 mentionedabove transmits airplane avionics data generated by airplane avionicsequipment, represented generally at 58, including airplane location,direction and flight pattern data as well as other data such as airplanepitch, roll and yaw data. The data from the airplane avionics equipment58 is input into and processed by a payload processor 60 before beingoutput to the telemetry antenna 52 through a telemetry modem 62. Thepayload processor 60 is also responsible for processing signalstransmitted to and received from the ground converter equipment 32through the feeder link 33 established between the C-band antennas 42,56 and for processing signals transmitted to and received from thesystem users 18 through a downlink, or user link, 69 established betweenthe users 18 and a payload downlink antenna such as an 800 MHz smartantenna 70, with the signals received by and transmitted from thepayload being appropriately upconverted or downconverted by an 800 MHzconverter 72 before being input into a beamformer 73. In accordance witha preferred embodiment of the present invention and as will be discussedbelow in more detail, the beamformer 73 controls the gain, direction,and associated footprint of each communications beam transmitted by thesmart antenna 70 to cause the transmitted beams to appear stationary tothe respective geographic areas covered by the beams, thereby minimizingcall hand-offs within the cells and optimizing the call capacity of eachcell. The payload 22, in addition to including the above-mentionedequipment, also includes GPS equipment 74 that can also be input intothe processor 60 and transmitted to the ground converter equipment 32 orto the airplane operations center 37 for flight control purposes. Thecomponents shown in the airplane and in the payload together form theairplane repeater that enables cellular coverage to be provided to alarge geographic area that may otherwise not support terrestrialcellular coverage due to an insufficient number of cell stations or thelike.

As should be appreciated from the system configuration shown in FIGS. 1and 2, both the airborne cellular system 10 and conventional terrestrialcellular systems appear identical to the PSTN 20 and the system users18. In other words, there are no discernable service-related differencesbetween calls linked to the PSTN 20 through the cellular infrastructure,radio infrastructure and airplane segments 12-16 and calls handledthrough a conventional terrestrial system infrastructure, in part due tothe fact that the cellular infrastructure segment 12 includes a standardtelephony switch in the MSO 24 and BTSs 30 a, 30 b that are identical tothose included in a conventional terrestrial system infrastructure.

Still referring to FIGS. 1 and 2, operation of the components of theairborne cellular system 10 during completion of a call made by one ofthe system users 18 will now be described. The airplane 35, whenon-station preferably flies in a circular or near circular flightpattern (although the flight pattern may vary according to specificweather and coverage conditions) to provide coverage to a predeterminedgeographic area during a mission that typically lasts about 6 hours.While it is on-station, the airplane maintains contact with the groundconverter equipment 32 to provide both the feeder link 33 and the userlink 69 for the cellular infrastructure segment 12 through the radioinfrastructure equipment segment 14. The airplane 35 also transmits apredetermined number of communications beams, such as, for example, 13beams, over the coverage area, with each beam being assigned to a sectorof one of the BTSs 30 a, 30 b and having its own set of control andtraffic channels to carry signaling and voice data between the systemusers 18 and the cellular infrastructure segment 12. As the airplane 35moves in its flight pattern, the beams radiated from the airplanerotate. Therefore, the system users 18 will “see” a different beam every45 seconds or so and the cellular infrastructure segment 12 performs asector to sector handoff of the call to keep the call from beingdropped.

When initiating a call, a system user, such as one of the users 18,utilizes the control channels in the beam to signal the MSO 24 torequest a call setup. The request is sent from a handset of the user 18to the airplane payload 22, and then is relayed to the ground converterequipment 32. The ground converter equipment 32 relays the request tothe corresponding BTS, such as the BTS 30 a. The BTS 30 a then transmitsthe request to the MSO 24, which sets up the call with the PSTN 20. Thepayload 22 therefore simply extends the physical layer of the BTS 30 tothe users 18 to allow a much wider area of coverage than would typicallybe provided by a conventional terrestrial system, and with lessassociated infrastructure buildout cost. The airborne system 10 is alsopreferable for providing temporary cellular coverage for special eventsareas, where coverage is only needed for several days, therebyeliminating the need and cost associated with erecting cell stations andthen tearing the cell stations down after the special events end.

Once the call setup is completed, voice communication with the PSTN 20through the traffic channels in the beam is initiated, and voiceinformation is then relayed in the same manner as the signalinginformation. When the call ends, a signal is sent to the MSO 24 to teardown the call, the handset of the user 18 releases the traffic channelused for voice communications, and the channel is returned to an idlestate.

FIG. 3 is a simplified signal flow diagram that shows the smart antenna70 in more detail and in accordance with a preferred embodiment of thepresent invention, as well as other components connected to the antenna70. The antenna 70 is a phased array antenna that may include severalpatch antenna elements, such as those shown generally at 80, that aremounted within a radome structure 82 that may be, for example, flat,cylindrical or spherical. It is contemplated that more than one phasedarray antenna will likely be used in the payload 22. For example, inaccordance with one embodiment of the present invention, three phasedarray antennas may be mounted to form a pyramid-shaped antenna array,with the a beamformer feeding each one of the antenna elements in thearray.

Signal flow to the antenna in the system forward link will now bediscussed, it with it being understood that signal flow is identical,albeit opposite in direction, in the system reverse link. The C-bandfeeder link antenna 56 receives signals by link 33 from the groundconverter antenna 42 (FIG. 2) and passes the signals to the converter72. The converter downconverts the signals from C-band signals to UHFsignals having a frequency of around 800 MHz before passing the signalsto the beamformer 73 over path 86. The beamformer 73 adjusts theamplitude and phase of the signals, under control of input 75, for eachof the antenna patch elements 80 in the antenna 70 (or array ofantennas) based on antenna gain coefficients generated in a manner aswill be described below in more detail. The antenna 70 receives thesignals from the beamformer 73 and radiates the signals to the groundbelow in the form of antenna beams, such as the beam 94 (FIG. 6). Eachantenna beam subsequently forms a footprint on the ground below thatdefines a communications cell to link calls within the cell to the PSTN20.

As noted below processor 60 utilizes airplane information such asposition, pitch, roll, yaw, etc. from avionics 58 and various load orload distribution, terrain conditions, and the like supplied from theMSO 24 or OMC 26 to generate the antenna element gain coefficients atinput 75. The information from the MSO 24, etc. is provided over thetelemetry link 34 from antenna 46, modem 48, processor 50, and controlterminal 54. Referring to FIG. 4, an exemplary beamformer is shown at85. The beamformer 85 is for forming beams for only one of the beamstransmitted by the antenna 70; however, a beamformer of identicalstructure and function would be implemented for each beam to betransmitted by the antenna 70. The beamformer receives beam signals tobe transmitted through a signal input 86, note this is an input for oneof a plurality of beamformers. A signal phase shifter and attenuator 87then subsequently and accordingly phase shifts and attenuates thesignals according to antenna gain coefficients at input 75 generated bya processor, such as the processor 60 in the payload 22. The phaseshifters and attenuators at 87 may be implemented either in analog formvia an RF phase shifter and variable attenuator under digital control,or digitally by an A/D, a complex multiplier, and a D/A. Elementamplifiers at 88 then amplify beam signals so that the radiated powerlevel is sufficient for the user links before the signals are passed toand transmitted from certain of the patch antenna elements 80 that areselected based on the antenna gain coefficients.

FIG. 5 shows the processor 60 in the payload 22 used to generate theantenna gain coefficients, as well as its relationship to the antennasystem 70 and the beamformer 73 in more detail. The processor 60generates the antenna gain coefficients based on data input from severalsources. A shape optimizer 90 in the ground converter equipment 32, oralternatively in the OMC 26, receives cell footprint data relating to,for example, call loading and potentially interfering adjacent cellularsystems, and that is stored in a fixed database maintained at the OMC 26or the MSO 24. The shape optimizer 90 uses the above data to compute thecell shape and location data. Specifically, as shown in FIG. 6, theshape optimizer 90 computes the direction of the major axis A_(maj) ofeach cell oval, such as the oval shown at 94, as well as the ratio ofthe oval major axis A_(maj) to its minor axis A_(min), otherwise knownas the oval eccentricity, in polar coordinates. The computed beam shapeand location data is then converted to GPS-based coordinates beforebeing transmitted to the processor 60 via the telemetry link 34.

In addition to receiving the cell GPS-based beam shape data, theprocessor 60 also receives aircraft telemetry data, including aircraftpitch, roll and yaw data, as well as airplane flight pattern locationdata, directly from the aircraft avionics equipment 58 of the airplane35. The processor 60 then calculates the antenna gain coefficientson-the-fly for the antenna elements 80 based on the data received fromboth the ground and the airplane, and outputs the coefficients to thebeamformer 73 to control the gain, direction, and shape, of each of thebeams radiated from the antenna 70.

Consequently, it is possible to maintain the antenna beams in a fixedposition relative to the ground by dynamically changing the beamsteering angles and incorporating fast switching of traffic betweenbeams transparent to the subscriber and cellular infrastructureequipment. The system handoff rate can therefore be maintained at alevel similar to that of a conventional cellular system, therebyreducing overall system cost.

While the antenna gain coefficients are described above as beingcalculated by the processor 60, the coefficients can also be calculatedby a terrestrial-based processor, such as the processor 50 in the groundconverter equipment 32, and transmitted to the beamformer 73 via thetelemetry link 34.

It should be noted at this point that cell shape and location attributescan be based on (1) the desired link margin, with smaller high gainbeams being generated to cover urban areas requiring high link marginfor building penetration, and with larger low gain beams being generatedto cover rural areas requiring less link margin; (2) terraincharacteristics, with smaller beams being generated to cover areas whereterrain could create large delay and Doppler spread, and with broaderbeams being generated to cover areas where terrain could create smallerdelay and Doppler characteristics, thereby reducing the performanceimpact of high delay/Doppler spread environments; (3) the distributionof cellular traffic load, with small beams being generated to cover highload density areas and with larger beams being generated to cover lowdensity areas, thereby improving the spectral efficiency, or amount ofload carried per unit bandwidth, of the system, and (4) the location ofother adjacent cellular systems with beam directions, size, and sidelobestructure generated to reduce interference with other cellular systems.As will now be described, the present invention is capable of shapingcommunications beams based on required link margin, terraincharacteristics, interference characteristics, and call traffic load.

In view of the above and with reference to FIGS. 7 and 8, the airplane35 is shown at a first flight pattern position in FIG. 7 at time t1.Beams radiated from the plane's smart antenna form beam pattern cells,or footprints, such as the exemplary footprints 100, 102, 104, 108,within a predetermined geographic area of coverage 110 (in actualoperation the airplane antenna would radiate, for example, 13 beams tocover the entire geographic area 110). When the airplane 35 moves to asecond flight pattern position at time t2 as shown in FIG. 8, the groundcoordinates of the footprints 100, 102, 104, 108, within thepredetermined geographic area of coverage 110 do not change. As aresult, the system 10 is not required to hand off calls within the areaof coverage 110 due to movement of the airplane 35.

Beam shape and sidelobe characteristics may be varied through the smartantenna in accordance with the present invention as a function of calltraffic load and distribution. For example, as shown in FIG. 7, at timet1 the beamformer 73 shapes beams covering a high delay spreadgeographical region having associated footprints such as that shown at100 so that the beam footprints are relatively small in size and high ingain, or link margin, within the smaller footprint area. The beamformeralso shapes beams covering a low call demand geographical region to haveassociated footprints such as that shown at 102 that are relativelylarge in size and low in gain, as the lower amount of call trafficwithin the footprint does not require a large amount of system power forlinking purposes.

The communications beams may also be shaped and sized based on adjacentbeam footprints from other cellular systems. For example, a beamcovering a low urban density geographical region has an associatedfootprint such as that shown at 104 that is relatively large in size andlow in gain due to the low number of system users in the area. Thebeamformer 73 shapes and sizes the beam footprint 104 and adjusts itslink margin based on the input beam coefficients to minimizeinterference with adjacent beam footprints, such as the footprint 106,of other cellular systems. Likewise, the beamformer 73 can adjust thesizes and shapes of beams covering high urban density geographicalregions based on the input beam coefficients so that the resulting beamshave associated footprints such as that shown at 108 that are relativelysmall in size and high in gain to support the high number of systemusers within the region and to minimize interference with the adjacentbeam footprint 106.

The above-described embodiment was directed to a single antenna arraysuch as the antenna 70 and a beamformer that controlled the gain andassociated footprint of each communications beam transmitted from theantenna 70. However, it should be appreciated that, in an alternateembodiment, the antenna could be formed from multiple planar antennas sothat fixed beam coverage on the ground could be maintained while at thesame time maintaining reasonable scan angles for each of the antennas.Such multiple antenna fixed beam coverage could be realized throughrapid switching of call load between beams in conjunction with changesin beam direction.

For example, the antenna 70 may be formed from three planar antennaseach having a 120 azimuthal field of view (with a +/−60 azimuthal scanangle) and each providing four communications beams to therefore enablethe system 10 to provide complete coverage over a 360 azimuthal field ofview. For example, each antenna may have associated beam pointingdirections relative to antenna boresight of −45, −15, 15 and 45 at aparticular point in the flight pattern of the airplane 35, with eachbeam having a width of 30. As the airplane continues to execute itscircular flight pattern, the four beams generated by each of the planarantennas are scanned to maintain a fixed beam position on the ground.For example, the airplane rotates within its flight pattern to a pointwhere the above beam pointing directions change to −30, 0, 30 and 60,respectively. If the beam pointing angles were shifted further from suchbeam pointing directions, large scan angles and poor antenna efficiencywould result.

Therefore, according with the presently-discussed alternativeembodiment, large scan angles can be avoided by switching trafficbetween beams via, for example, a switch in the converter 72 or in aground-based converter such as the converter 44 and resetting the beamscan angles via the beamformer processor 60. Consequently, for example,the load from a fourth beam from a first planar antenna would beswitched to a fourth beam of a second planar antenna, the load on thefourth beam of the second planar antenna would be switched to the fourthbeam of a third planar antenna, and the load on the fourth beam of thethird antenna would be switched to the fourth beam of the first antenna.Simultaneously, the steering direction of the fourth beams from allthree antennas would be switched from 60 to −60. As a result, the scanangles of all three antennas are maintained within a reasonable range,while fixed beam coverage is maintained on the ground.

In view of the foregoing discussion, it should now be appreciated that,by enabling the beam steering angles and beam shapes to be controlled,the smart antenna in accordance with the present invention enables cellboundaries and/or sizes to be varied as a function of cell load, therebyimproving system performance and spectral capacity, reducing system costby enabling smaller power amplifiers to be used in the beamformer, andreducing payload power consumption. By enabling the beam steering anglesand beam shapes to be controlled, the smart antenna in accordance withthe present invention also is capable of reducing multipath Dopplerspread within a cell without having to replace or reconfigure payloadhardware, thereby making the overall system more robust, flexible andcost effective. Further, by maintaining beam pointing even in thepresence of airplane pitch, roll and yaw, the smart antenna inaccordance with the present invention is able to maintain compliancewith FCC regulations regarding tall-tower radiation to the horizon andinterference with other cellular systems. In addition, a smart antennain accordance with the present invention can also shape communicationsbeams output therefrom to facilitate frequency coordination betweenmultiple airborne cellular systems, and/or between airborne andterrestrial cellular systems.

While the above description is of the preferred embodiment of thepresent invention, it should be appreciated that the invention may bemodified, altered, or varied without deviating from the scope and fairmeaning of the following claims.

What is claimed is:
 1. An aircraft-based cellular communications system,comprising: a base transceiving station for switching calls to calldestinations; an aircraft including a beamformer for generatingcommunications beams, an antenna having a plurality of antenna elementsand corresponding amplifiers for transmitting the beams to formterrestrial communications cells that create a link between wirelesscommunications devices within the terrestrial cells and the basetransceiving station, and a telemetry link between the base transceivingstation and the beamformer; the base transceiving station including abeam shape optimizer for computing a complex gain of the antennaamplifiers based on mapping of the aircraft flight and location data tostored communications coverage cell coefficient data and fortransmitting the complex gain to the antenna amplifiers of thebeamformer via the telemetry link to control shapes of each of thecommunications coverage cells.
 2. The aircraft-based cellularcommunications system of claim 1, wherein the beam shape optimizerdynamically computes the complex gain of the antenna amplifiers tocompensate for beam pattern movement caused by movement of the aircraft.3. The aircraft-based cellular communications system of claim 2, whereinthe movement of the aircraft comprises airplane pitch, roll and yaw. 4.The aircraft-based cellular communications system of claim 1, whereinthe beam shape optimizer dynamically computes the complex gain of theantenna amplifiers to adjust each of the geographic communicationscoverage cells based on population within the cell.
 5. Theaircraft-based cellular communications system of claim 1, wherein thebeam shape optimizer dynamically computes the complex gain of theantenna amplifiers to minimize interference with geographiccommunications coverage cells of other systems.
 6. The aircraft-basedcellular communications system of claim 1, wherein the beam shapeoptimizer dynamically computes the complex gain of the antenna elementsto minimize beam interference and thereby reduce overall system loading.7. The aircraft-based cellular communications system of claim 1, whereinthe beam shape optimizer dynamically computes the complex gain of theantenna elements to reduce angular spread on transmit and receive pathsof antenna element beams to thereby reduce multipath Doppler spreadwithin each geographic communications coverage cell of each of themultiple antenna elements.
 8. The aircraft-based cellular communicationssystem of claim 1, wherein the beam shape optimizer dynamically computesthe complex gain of the antenna elements to re-allocate call trafficwithin the geographic communications coverage cell of each of themmultiple antenna elements to provide for more even system calldistribution.
 9. An optimizer for shaping communications beamstransmitted from an airborne wireless communications system repeaterantenna array, comprising a processor for computing a complex gainassociated with the antenna array based on mapping of repeater locationdata to stored communications coverage cell coefficient data, and fortransmitting the complex gain to the antenna array to optimize shapes ofeach of the communications coverage cells.
 10. The optimizer of claim 9,wherein the processor is implemented with the airborne repeater.
 11. Theoptimizer of claim 9, wherein the processor is implemented in aterrestrial base transceiving station and communicates with the antennaarray via a telemetry link.
 12. A method of managing operation of anairborne repeater antenna array comprising: receiving at least one ofairplane telemetry data indicating an airplane flight pattern location,adjacent cellular system beam footprint data, and call distribution loadwithin an airplane beam footprint; computing desired beam direction andshape parameters based on the at least one of airplane telemetry dataindicating an airplane flight pattern location, adjacent cellular systembeam footprint data, and call distribution load within an airplane beamfootprint; and calculating complex gains for each of multiple antennaelements to form a set of communications beams each having a desireddirection and shape to thereby form terrestrial cells with correspondinglocations and shapes.
 13. The method of claim 12, wherein the computingof desired beam direction and shape parameters and the calculating of acomplex gain for each of multiple antenna elements compensates for beampattern movement caused by airplane movement.
 14. The method of claim13, wherein the airplane movement comprises airplane pitch, roll andyaw.
 15. The method of claim 12, wherein the computing of desired beamdirection and shape parameters and the calculating of a complex gain foreach of multiple antenna elements comprise adjusting the communicationsbeams to adjust the terrestrial cells based on population within each ofthe terrestrial cells.
 16. The method of claim 12, wherein the computingof desired beam direction and shape parameters and the calculating of acomplex gain for each of multiple antenna elements are performed tominimize interference with geographic communications coverage cells ofother systems.
 17. The method of claim 12, wherein the computing ofdesired beam direction and shape parameters and the calculating of acomplex gain for each of multiple antenna elements comprise dynamicallycomputing beam patterns of the communications beams to minimizeinter-beam interference and thereby reduce overall system loading. 18.The method of claim 12, wherein the computing of desired beam directionand shape parameters and the calculating of a complex gain for each ofmultiple antenna elements accounts for angular spread of incident energyto reduce Doppler and delay spread impact.
 19. The method of claim 12,wherein the computing of desired beam direction and shape parameters andthe calculating of a complex gain for each of multiple antenna elementsreallocates call traffic within the airplane beam footprint to balanceload between the terrestrial cells.
 20. A method of managing operationof an airborne repeater antenna including multiple planar antennascomprising: receiving at least one of airplane telemetry data indicatingan airplane flight pattern location, adjacent cellular system beamfootprint data, and call distribution load within an airplane beamfootprint; computing desired beam direction and shape parameters basedon the at least one of airplane telemetry data indicating an airplaneflight pattern location, adjacent cellular system beam footprint data,and call distribution load within an airplane beam footprint; andcalculating a complex gain for multiple antenna elements for each ofmultiple planar antennas to form a set of communications beams eachhaving a desired direction and shape to thereby form terrestrial cellswith corresponding locations and shapes; and switching beam trafficamong the multiple antennas to maintain antenna scan angles within apredetermined range.
 21. The method of claim 20, further comprisingswitching steering directions of each of the multiple planar antennassimultaneously with the switching of beam traffic among the multipleantennas to maintain antenna scan angles within a predetermined range.